In recent years, a wireless communication device mounted in, for example, a vehicle is configured such that a transmitter and a receiver for signal processing in a wireless frequency band are integrated into one body in order to achieve a size reduction. When a transmitter and a receiver are integrated into one body, the transmitter and the receiver may be electrically coupled in a high frequency component and may oscillate abnormally. Moreover, because amplifiers with high amplification factors are used in the transmitter and the receiver for the sake of power amplification, a signal on an output side of the transmitter or receiver may reach an input side and oscillate abnormally. A proposed method of detecting this kind of abnormal oscillation includes determining abnormal oscillation based on a preset threshold and an input level of a radio wave, which is from the exterior and received by an antenna (refer to PTL 1).